Bottom Gate OLED Transistor Channel Protection
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Solution Overview
Problem
The channel layer in organic electroluminescent devices is exposed to external light, causing device characteristic changes, which complicates the fabrication process and requires additional light blocking patterns.
Innovation Solution
The active-matrix organic electroluminescent device employs a bottom gate structure with a stopper on the gate electrode and connects the stopper to the source electrode to minimize device characteristic changes and protect the channel layer, using a metal layer and indium tin oxide electrode for top-emission types to block light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a light blocking pattern is added to protect the channel layer from external light, then the channel layer is protected from light exposure, but the fabrication process becomes complicated
Solution Approach 1:
The gate electrode is designed to serve dual functions: as the control electrode for the thin film transistor and as a light-blocking structure to protect the channel layer. By making the gate electrode extend beyond the channel layer boundaries, it simultaneously performs electrical control and optical shielding, eliminating the need for separate light blocking patterns and simplifying the fabrication process
Solution Approach 2:
The invention merges the light-blocking function with the gate electrode structure. Instead of adding a separate light blocking layer or pattern, the gate electrode itself is configured to cover and protect the channel layer from external light, combining two previously separate functions into a single integrated component
2Device complexity
If the channel layer is exposed to external light, then the device structure remains simple, but the device characteristic changes due to light energy
Solution Approach 1:
The gate electrode is extended in the planar dimension beyond the channel layer boundaries, creating an overlapping region. This dimensional extension allows the gate electrode to provide lateral coverage and protect the channel layer from light exposure without adding vertical complexity or requiring additional layers, maintaining structural simplicity while improving reliability
Data Source
AI summary
An organic electroluminescent device is provided. A gate line and a data line cross each other to define a pixel region, and a power line crosses the gate line and is arranged parallel to the data line. A switching transistor is disposed at a crossing of the gate line and the data line, a driving transistor is disposed at a crossing of the gate line and the power line, and a pixel electrode is formed in the pixel region. Each of the switching transistor and the driving transistor includes a gate electrode formed under a channel layer, and a stopper on the channel layer.